Electric motors are increasingly installed in modern motor vehicles. Said electric motors are used in this context, in particular, as drive motors which are fully integrated in the drive train or, for example, as starter generators or axle-mounted motors in hybrid applications. In this context, partially externally excited synchronous machines are used which have a rotor composed of a laminated core provided with an exciter winding. In such rotors, grooves are formed between the wound pole teeth.
During operation, high centrifugal forces, which can pull the exciter winding out of the grooves, occur both in the case of internal rotors as well as in the case of external rotors. The centrifugal forces are dependent on the rotational speed and on the weight of the groove-internal components. In particular in the case of revving up machines the winding is therefore additionally secured after assembly. For this purpose, various bonding agents are known which are used as impregnating resins or casting compounds.
In addition, groove stoppers or groove wedges can be used in order to prevent the winding dropping out of the groove. Such groove wedges are known, for example, from document DE 28 17 951 A1. In the case of rotors which are configured for electric motors with a high rotational speed (10,000 revolutions per minute and more) it would be appropriate to secure the groove-internal components, in particular the exciter winding, even more effectively against centrifugal forces which occur during operation.